<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
	<style type="text/css">
		*{
			padding: 0;
			margin: 0;
		}
		.box{
			position: absolute;
		/*	top: 0;
			bottom: 0;
			left: 0;
			right: 0;*/
			width: 100%;
			height: 100%;
			background: red;
			/*		
				绝对定位实现背景全屏：
					1.设置四个方位都是0
					2.设置宽高100%


				*/
		}
	</style>
</head>
<body>
	<div class="box"></div>
</body>
</html>